On Thu, Oct 23, 2014 at 3:04 PM, John Griffith <john.griffi...@gmail.com> wrote:
The debate about whether to wipe LV's pretty much massively depends on the >> intelligence of the underlying store. If the lower level storage never >> returns accidental information ... explicit zeroes are not needed. >> > > On Thu, Oct 23, 2014 at 3:44 PM, Preston L. Bannister < > pres...@bannister.us> wrote: > >> Yes, that is pretty much the key. >> >> Does LVM let you read physical blocks that have never been written? Or >> zero out virgin segments on read? If not, then "dd" of zeroes is a way of >> doing the right thing (if *very* expensive). >> > > Yeah... so that's the crux of the issue on LVM (Thick). It's quite > possible for a new LV to be allocated from the VG and a block from a > previous LV can be allocated. So in essence if somebody were to sit there > in a cloud env and just create volumes and read the blocks over and over > and over they could gather some previous or other tenants data (or pieces > of it at any rate). It's def the "right" thing to do if you're in an env > where you need some level of security between tenants. There are other > ways to solve it of course but this is what we've got. > Has anyone raised this issue with the LVM folk? Returning zeros on unwritten blocks would require a bit of extra bookkeeping, but a lot more efficient overall.
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